Module 1: Soil formation, functions and threats Flashcards
(26 cards)
Why are soils important?
We rely on soils to produce food. As soil formation is a slow process (10cm in 2,000 years) it is important to preserve the soil we have.
What are major threats to soil?
- loss of soil organics matter
- water and wind erosion
- sealing for urbanisation
- salinisation
- contamination, toxification, pollution
- nutrient imbalances
- soil biodiversity decline
- loss of wettability (when soil does not infiltrate, filter, or redistribute)
How do you identify the structure and texture of soil?
What is the ISRIC SoilGrids?
ISRIC is the world data centre for soil.
How are soils formed?
By the following five factors discovered by Dokuchaev:
1) Parent material
2) Climate
3) Vegetation
4) Time
5) Topography
The most recently added factor:
6) People
What are key soil functions?
1) Plants grow in soils for food, fuel and fibre.
2) Construction materials, e.g. wood, bricks, …
3) Foundation to life on, e.g. infrastructure
4) Water storage, quantity-, & quality management
5) An important habitat for a lot of species. 24% of the total global biodiversity lives in the soil.
6) Nutrient cycling and mineralisation (=breaking down of dead organic material).
7) Climate regulation and carbon sequestration.
What is the FAO?
The Food and Agriculture Organisation of the United Nations.
What are ‘soil ecosystem services’? + examples
Soil ecosystem services are the benefits we receive from soil functions. E.g. healthy food, fresh water, flood control …
What is a lysimeter?
A tool to investigate the filtering capacity of the soil. It captures the soil solutions (=liquids) passing through the soil at different depths.
What is a spiritual link to mineralisation and nutrient cycling?
When we die the minerals in us are eventually cycled back into the soil. Technically we are soil, just temporarily in a human form.
What gives soils their dark brown colour?
The soil organic matter which is carbon locked up in the soil.
What is soil texture?
Soil texture are the mineral inorganic components of the soil and their relative proportions to each other (sand, silt and clay).
What are the main classes of soil texture? And what are their points of distinction?
Sand (coarse), silt (fine), and clay (fine soil). Sometimes gravel is also in the soil.
What is loam?
A soil is called loam when there is an equal combination of sand, silt, and clay.
What does the soil texture influence?
Water-holding capacity, permeability (infiltration rate), nutrient retention, erodibility, soil biological activity …
What is soil structure?
Soil structure informs us about how the solid soil particles are arranged, meaning how they are bound together and aggregated.
What is the difference between soil structure and soil texture?
Where soil texture looks are the size of the particles and their relative proportions (sand, silt and clay) soil structure looks at how the aggregates are arranged.
What are soil peds? What forms them? What keeps them together?
A synonym for soil peds is soil aggregates. They can be formed by freezing, thawing, meeting, drying, fungi, roots, tillage. Clay, iron oxides, and soil organic matter.
What are some examples of soil structures? What is the most preferable soil structure for agriculture?
Granular soil.
What are soil qualities?
Soil texture and soil structure.
What is soil degradation? Provide examples.
Soil degradation s the decline in soil chemical, physical, and biological qualities due to improper management of it, usually for agriculture, pastoral, industrial or urban reasons.
Examples are loss of soil organic matter, soil compaction, salinity, erosion, loss of fertility.
What is land degradation and how does it differ from soil degradation?
Land degradation describes how land resources like air, soil, vegetation, water, climate, relief, rocks, have changed for the worst. Soil degradation is an indicator of land degradation.
What is desertification?
Desertification is land degradation in drylands areas as a result of human activities and climate variation.
What are some of the drivers, types, and consequences of soil degradation?
